Since only a small number of high-pressure injection valves actually spray-discharge the fuel jet along the extension of the longitudinal valve axis, but the spray is usually inclined relative to the longitudinal valve axis, the spray orifices usually being disposed asymmetrically in addition, it is important to fix the high-pressure injector in place inside the cylinder head into which it is inserted in a manner that prevents a rotation of the valve and ensures that the spray angle always conforms to the layout.
Conventional approaches for the fixation of a high-pressure injector in a cylinder head include, for example, the provision of a rib on one section of the outer periphery of the valve body to be inserted into the cylinder head, which rib then engages with a groove correspondingly provided in the cylinder head. However, this requires the groove to be cut into the cylinder head. In addition, due to the lack of space, guide bevels to facilitate the insertion of the valve during installation in the cylinder head are unable to be provided in the region where the rib engages with the cut groove. Because such guide bevels are lacking, the installation of the high-pressure injector in the cylinder head becomes more difficult, and an installation of an FCA, i.e., a rail in which a plurality of valves are already installed, in which case all high-pressure valves with the rail must then be installed in the cylinder head simultaneously, is even next to impossible or at least not suitable for mass production since all valves must be readjusted according to their position during the installation.
Another solution for the positional fixation of a high-pressure injector in a cylinder head is the known use of a holding-down clamp, which then transmits the position to the rail and to the cylinder head.
However, a transmission of the position from the high-pressure injector to the holding-down clamp and then to the rail is possible only if the use of a corresponding holding-down clamp is an option, and if a corresponding cut—in this case, a width over flats of hexagonal nuts—is provided.
A fuel-injection system for the direct injection of fuel into a combustion chamber of an internal combustion engine is described in DE 197 35 665, for example, in which a receiving bore for each fuel injector is provided in the cylinder head to accommodate the spray-discharge section of the fuel injector, the receiving bore terminating in the associated combustion chamber. The receiving bore is implemented in the form of a stepped bore and has a tapering section against which a first sealing element rests in sealing manner and seals the spray-discharge section from the cylinder head. The fuel injector is supported on the first sealing element, which is implemented as O-ring, in a manner allowing rotation, in such a way that the fuel injector is able to pivot slightly within specified limits about a solid angle α. The system described in DE 197 35 665 allows the fuel injector to be tilted relative to the longitudinal axle within solid angular range α, a clamping shoe making it possible to transmit sufficient holding-down force to the fuel injector within the entire tilting range. The fuel injectors are rigidly fixed in place on the cylinder head by tightening clamping bolts of the clamping shoes, which can be screwed into the cylinder head.
However, conventional approaches for the fixation of the high-pressure injectors have the disadvantage that their implementation entails expensive cutting processes.